1. Field of the Invention
The present invention relates to a radio terminal belonging to a radio network for carrying out communications by setting up logical channels on a radio network in advance and an information transfer method of a radio terminal, as well as to a radio gateway device for connecting an IEEE 1394 bus with a radio network for carrying out communications by setting up logical channels on a radio network in advance and an information transfer method of a radio gateway device.
2. Description of the Background Art
In recent years, the realization of home network is attracting much attention, and in particular, the IEEE 1394 bus for connecting between digital home electronic devices has been attracting considerable attention. The IEEE 1394 bus is capable of connecting a plurality of IEEE nodes in daisy chain or star connection and transferring a wideband data in excess of 100 Mbps. Also, it has a major feature that it is possible to transmit both asynchronous data and isochronous data on the same cable. For this reason, even though the IEEE 1394 bus was originally developed as a next generation version of SCSI, there are increasing trends to use the IEEE 1394 bus as a cable for connecting AV devices.
On the other hand, the realization of fast radio network (radio LAN) is also attracting attention. In particular, since the determination of the IEEE 802.11 specification in 1998, many radio LAN products are appearing in the market and there has been a remarkable decrease in the prices of these radio LAN products.
In conjunction with this trend for improved performance and reduced cost of the radio technology, there is an active trend to consider applications of the radio technology to the home environment and this trend is expected to grow further in future as can be anticipated by establishment of organizations of related companies such as HomeRF and Bluetooth (a kind of radio system using 2.4 GHz band) in the U.S.A. Also, from a viewpoint of the home network, the radio system is an easily acceptable system as it does not require any new cable construction. For this reason, a network system merging the IEEE 1394 bus and the fast and inexpensive radio LAN system is expected to play a central role in the future home network.
In such an environment for merging the IEEE 1394 bus and the radio network, there are several outstanding problems.
For example, one of the problems is how a protocol executed on the IEEE 1394 bus (a protocol presupposing the IEEE 1394 at the datalink layer such as AV/C protocol) can be executed over the radio network. In particular, in the case of executing a protocol such as the AV/C protocol in which message types (command, response, etc.) on the protocol are identified by logical addresses (registers) on the IEEE 1394 bus (where a value indicating an AV/C command or a value indicating an AV/C response can be found by reading a register according to an offset value described in a packet), identifiers corresponding to the logical addresses on that IEEE 1394 bus must also be provided at the radio LAN side. This situation is similar in the case of executing the AV/C protocol or the like between radio terminals.
It is therefore an object of the present invention to provide a radio terminal and its information transfer method which are capable of executing the AV control protocol by expanding it over to a radio network for executing data transfer after establishing a logical connection between radio terminals prior to data transfer between radio terminals.
It is another object of the present invention to provide a radio gateway device and its information transfer method which are capable of executing the AV control protocol by expanding it over to a radio network at a radio gateway for connecting the IEEE 1394 bus with a radio network for executing data transfer after establishing a logical connection between radio terminals prior to data transfer between radio terminals.
According to one aspect of the present invention there is provided an information transfer method for transferring information regarding an AV control protocol in a radio system for carrying out data transfer after establishing a logical connection between radio terminals or gateways prior to data transfer between radio terminals or gateways, the method comprising the steps of: exchanging signaling packets for signaling at a datalink layer between the radio terminals or gateways prior to an exchange of data packets on which the information regarding the AV control protocol is loaded, each signaling packet containing a channel identifier indicating a logical channel that is set up for transferring the data packets and a protocol identifier indicating the AV control protocol, such that a signaling packet transmitted from each radio terminal or gateway indicates a channel identifier that is set up for the each radio terminal or gateway and a signaling packet received from a correspondent radio terminal or gateway indicates a channel identifier that is set up for the correspondent radio terminal or gateway; storing at the each radio terminal or gateway a correspondence information obtained through an exchange of the signaling packets, the correspondence information indicating a correspondence among the protocol identifier, the channel identifier that is set up for the each radio terminal or gateway, and the channel identifier that is set up for the correspondent radio terminal or gateway; and transferring the data packets between the radio terminals or gateways, according to the correspondence information.
According to another aspect of the present invention there is provided an information transfer method for transferring information regarding an AV control protocol at a radio gateway connecting an IEEE 1394 bus with a radio network for carrying out data transfer after establishing a logical connection between radio terminals or gateways prior to data transfer between radio terminals or gateways, the method comprising the steps of: exchanging signaling packets for signaling at a datalink layer with a correspondent radio terminal or gateway on the radio network prior to an exchange of data packets on which the information regarding the AV control protocol is loaded, each signaling packet containing a channel identifier indicating a logical channel that is set up for transferring the data packets and a protocol identifier indicating the AV control protocol, such that a signaling packet transmitted from the radio gateway indicates a channel identifier that is set up for the radio gateway and a signaling packet received from the correspondent radio terminal or gateway indicates a channel identifier that is set up for the correspondent radio terminal or gateway; storing a correspondence information obtained through an exchange of the signaling packets, the correspondence information indicating a correspondence among the protocol identifier, the channel identifier that is set up for the radio gateway, and the channel identifier that is set up for the correspondent radio terminal or gateway; and transferring the data packets from a radio network side to an IEEE 1394 bus side or from the IEEE 1394 bus side to the radio network side, according to the correspondence information.
According to another aspect of the present invention there is provided a radio terminal device in a radio system for carrying out data transfer after establishing a logical connection between radio terminals or gateways prior to data transfer between radio terminals or gateways, the radio terminal device comprising: a signaling packet exchange unit configured to exchange signaling packets for signaling at a datalink layer with a correspondent radio terminal or gateway prior to an exchange of data packets on which the information regarding the AV control protocol is loaded, each signaling packet containing a channel identifier indicating a logical channel that is set up for transferring the data packets and a protocol identifier indicating the AV control protocol, such that a signaling packet transmitted from the radio terminal device indicates a channel identifier that is set up for the radio terminal device and a signaling packet received from the correspondent radio terminal or gateway indicates a channel identifier that is set up for the correspondent radio terminal or gateway; a memory unit configured to store a correspondence information obtained through an exchange of the signaling packets, the correspondence information indicating a correspondence among the protocol identifier, the channel identifier that is set up for the radio terminal device, and the channel identifier that is set up for the correspondent radio terminal or gateway; and a data packet exchange unit configured to exchange the data packets with the correspondent radio terminal or gateway, according to the correspondence information.
According to another aspect of the present invention there is provided a radio gateway device connecting an IEEE 1394 bus with a radio network for carrying out data transfer after establishing a logical connection between radio terminals or gateways prior to data transfer between radio terminals or gateways, the radio gateway device comprising: a signaling packet exchange unit configured to exchange signaling packets for signaling at a datalink layer with a correspondent radio terminal or gateway on the radio network prior to an exchange of data packets on which information regarding an AV control protocol is loaded, each signaling packet containing a channel identifier indicating a logical channel that is set up for transferring the data packets and a protocol identifier indicating the AV control protocol, such that a signaling packet transmitted from the radio gateway device indicates a channel identifier that is set up for the radio gateway device and a signaling packet received from the correspondent radio terminal or gateway indicates a channel identifier that is set up for the correspondent radio terminal or gateway; a memory unit configured to store a correspondence information obtained through an exchange of the signaling packets, the correspondence information indicating a correspondence among the protocol identifier, the channel identifier that is set up for the radio gateway device, and the channel identifier that is set up for the correspondent radio terminal or gateway; and a data packet transfer unit configured to transfer the data packets from a radio network side to an IEEE 1394 bus side or from the IEEE 1394 bus side to the radio network side, according to the correspondence information.
According to another aspect of the present invention there is provided a computer usable medium having computer readable program codes embodied therein for causing a computer to function as a radio terminal device in a radio system for carrying out data transfer after establishing a logical connection between radio terminals or gateways prior to data transfer between radio terminals or gateways, the computer readable program codes include: a first computer readable program code for causing said computer to exchange signaling packets for signaling at a datalink layer with a correspondent radio terminal or gateway prior to an exchange of data packets on which the information regarding the AV control protocol is loaded, each signaling packet containing a channel identifier indicating a logical channel that is set up for transferring the data packets and a protocol identifier indicating the AV control protocol, such that a signaling packet transmitted from the radio terminal device indicates a channel identifier that is set up for the radio terminal device and a signaling packet received from the correspondent radio terminal or gateway indicates a channel identifier that is set up for the correspondent radio terminal or gateway; a second computer readable program code for causing said computer to store a correspondence information obtained through an exchange of the signaling packets, the correspondence information indicating a correspondence among the protocol identifier, the channel identifier that is set up for the radio terminal device, and the channel identifier that is set up for the correspondent radio terminal or gateway; and a third computer readable program code for causing said computer to exchange the data packets with the correspondent radio terminal or gateway, according to the correspondence information.
According to another aspect of the present invention there is provided a computer usable medium having computer readable program codes embodied therein for causing a computer to function as a radio gateway device connecting an IEEE 1394 bus with a radio network for carrying out data transfer after establishing a logical connection between radio terminals or gateways prior to data transfer between radio terminals or gateways, the computer readable program codes include: a first computer readable program code for causing said computer to exchange signaling packets at a datalink layer with a correspondent radio terminal or gateway on the radio network prior to an exchange of data packets on which information regarding an AV control protocol is loaded, each signaling packet containing a channel identifier indicating a logical channel that is set up for transferring the data packets and a protocol identifier indicating the AV control protocol, such that a signaling packet transmitted from the radio gateway device indicates a channel identifier that is set up for the radio gateway device and a signaling packet received from the correspondent radio terminal or gateway indicates a channel identifier that is set up for the correspondent radio terminal or gateway; a second computer readable program code for causing said computer to store a correspondence information obtained through an exchange of the signaling packets, the correspondence information indicating a correspondence among the protocol identifier, the channel identifier that is set up for the radio gateway device, and the channel identifier that is set up for the correspondent radio terminal or gateway; and a third computer readable program code for causing said computer to transfer the data packets from a radio network side to an IEEE 1394 bus side or from the IEEE 1394 bus side to the radio network side, according to the correspondence information.
Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.